SALINAS, Calif. - A California farm that issued a voluntary lettuce recall over listeria contamination concerns says its notice has gone out to Minnesota, 18 other states and Canada.

True Leaf Farms of Salinas initially announced a recall of 90 cartons of romaine lettuce shipped to Oregon, Idaho and Washington.

But the chief executive of Church Brothers, which sells and markets the farm's produce, clarified Saturday that the recall involves nearly 2,500 cartons.

CEO Steve Church says most cartons went to institutions such as restaurants and cafeterias, which were notified about the recall. He says only 90 cartons went to retail sales, and those were from a stores in Oregon, Washington and Idaho.

The company issued the recall after a random check by federal officials found a sample tested positive for listeria. No illnesses were reported.